It is well known that electronic circuitry comprising image display apparatus can exhibit electronic characteristics which generate unwanted signal components that can degrade the displayed image or acoustic output signal. Many methods are known for linearizing circuit operation or reducing harmonic generation to prevent impairment of the audio or visual performance of the device. However, these efforts are directed to the prevention of degraded display performance with little or no regard to unwanted or unintentional emissions emanating from the display device.
A recently introduced Federal Communications Commission rule, 47 CFR .sctn. 15 subpart B, Unintentional Radiators, mandates levels of radiation for various electronic products including, for example, TV broadcast receivers, TV interface devices, cable system terminal devices, other receivers, personal computers and peripheral equipment. Specifically, all TV broadcast receivers offered for sale in the United States must comply with section rule 47 CFR .sctn. 15.117.
Although engineering efforts have been directed to the improvement of display image quality by the elimination of spurious image degrading artifacts, the desire to achieve the enhanced performance provided by the ATSC standards requires, among other things, wider circuit bandwidth and with attendant high frequency signal currents and voltages. Such wider bandwidth signals, while necessary to provide the desired level of enhanced performance, can unfortunately and inherently result in unintentional emissions with levels greater than those mandated by the FCC.